Downhole tools have been widely used in oil and gas industries. Many downhole tools comprise pressure-actuatable valves. For example, a prior-art ball-actuated sliding valve comprises a tubular valve housing having a bore and receiving in the bore a sliding sleeve. The sliding sleeve comprises a ball seat at an uphole end thereof, and is initially configured to an uphole closed position blocking one or more fluid ports on the sidewall of the valve housing. To actuate the sliding valve, a ball is dropped and seats against the ball seat of the sliding sleeve. Then, a fluid pressure is applied to the ball to actuate the sliding sleeve downhole to an open position to open the fluid ports on the valve housing.
One or more ball-actuated sliding valves may be used in a fracking process for fracking a subterranean formation. However, an issue in cascading a plurality of ball-actuated sliding valves for fracking is that the bore of a downhole sliding valve has to be smaller than that of the sliding valves uphole thereof to allow a smaller-size ball to pass through those uphole sliding valves to reach the target downhole sliding valve. In other words, the bores of the cascaded sliding valves have to reduce from uphole to downhole to ensure successful operation, thereby causing reduced flow rate at the downhole end.
U.S. Pat. No. 4,043,392 to Gazda teaches a well system for selectively locking well tools along a flow conductor in a well bore and a tool string for use in the flow conductor including a locking mandrel, a sleeve shifting device, and a well safety valve. The selective locking system has a landing and locking recess profile including both upwardly and downwardly facing stop shoulders. One form of the locking system is in a sliding sleeve valve including a cam release shoulder to free a selector and locking key when the sleeve valve is moved between spaced longitudinal locations. Another form of the locking system may be along a landing nipple and require that the well tool locked therein be disabled for release of the selector and locking tools. The sleeve shifting device has means for opening and closing the sliding sleeve valve including keys having upwardly and downwardly facing stop shoulders and recess profiles which are compatible with the landing and locking recess profile of the sleeve valve or of a landing nipple. The sleeve shifting device may be used also as a locking mandrel. Selectivity is provided by variation in the landing and locking profiles and the key profiles.
In U.S. Pat. No. 4,043,392, the spring-biased key profiles are mutually exclusive. A key profile will only engage a slidable sleeve with a mating internal profile.
U.S. Pat. No. 4,436,152 to Fisher, et al. teaches an improved shifting tool connectable in a well tool string and useful to engage and position a slidable sleeve in a sliding sleeve device in a well flow conductor. The selectively profiled shifting tool keys provide better fit with and more contact area between keys and slidable sleeves. When the engaged slidable sleeve cannot be moved up and the shifting tool is not automatically disengaged, emergency disengagement means may be utilized by applying upward force to the shifting tool sufficient to shear pins and cause all keys to be cammed inwardly at both ends to completely disengage for removal of the shifting tool from the sliding sleeve device.
U.S. Pat. No. 5,305,833 to Collins teaches a shifting tool for sliding sleeve valves for use in oil and gas wells which has locating dogs that are used for selectively locating and engaging a shoulder inside the valve. Primary keys engage and selectively shift the sliding sleeve to an equalized position as well as prevent premature shifting to a fully open position. Also included is apparatus for selectively overriding the shifting prevention following equalization. Secondary keys lead the primary keys in the shifting direction and engage the sleeve and move it to the fully open detent position. There is also selective disengagement of the shifting tool from the sleeve valve to allow withdrawal of the shifting tool form the well. Furthermore, a method for selectively and sequentially shifting the sliding sleeve for a sliding sleeve valve from the closed to equalizing position, and then from the equalizing to fully open position is disclosed.
In particular, U.S. Pat. No. 5,305,833 teaches two separate spring biased keys, wherein a first of the two keys can fit in the profile of a second of the two keys. However, the second key cannot fit in the profile of the first key.
U.S. Pat. No. 5,309,988 to Shy, et al. teaches a subsurface well flow control system including a series of movable sleeve type flow control devices installed in a well flow conductor at various fluid-containing fracture zones, and a shifter tool movable through the conductor and operable to selectively shift any selected number of the sleeve portions of the flow control devices, in either direction between their open and closed positions, without removing the tool from the conductor. Radially retractable anchor and shifter key sets are carried in sidewall openings of the tool body, and are respectively configured to be lockingly engaged with interior side surface groove sets on the body and movable sleeve portions of any of the flow control devices. The key sets are spring-biased radially outwardly toward extended positions, and an electromechanical drive system disposed within the tool body is operative to radially retract the key sets, and to axially drive the shifter key set toward or away from the anchor key set. This permits the tool to be moved into and through any of the flow control devices in either axial direction, locked to the device, operated to shift its sleeve portion fully or partially in either direction, and then disengaged from the flow control device and moved to any other one of the flow control devices to shift its sleeve portion. Interengaged V-threads on the body and sleeve portions of each flow control device facilitate the releasable retention of the sleeve portion in a partially shifted position.
U.S. Pat. No. 5,309,988 also teaches two mutually exclusive key profiles.
U.S. Pat. No. 5,730,224 to Williamson, et al. teaches a subterranean structure for controlling tool access to a lateral wellbore extending from a wellbore. The subterranean structure comprises a bushing that is located in the wellbore and proximate an opening to the lateral wellbore and that has an access window therethrough for allowing access by a tool to the lateral well through the opening. The bushing further has a slidable access control device coaxially coupled thereto. Also included is a shifter that is engageable with the slidable access control device to cause the slidable access control device to slide between an open position wherein a tool is allowed to pass through the window and the opening and into the lateral wellbore and a closed position wherein the tool is prevented from passing through the window and the opening and into the lateral wellbore. Such patent further teaches a method of controlling tool access to a lateral wellbore extending from a wellbore. The preferred method comprises the steps of: 1) locating a bushing in the wellbore proximate an opening to the lateral wellbore, the bushing having an access window therethrough for allowing access by a tool to the lateral wellbore through the opening, the bushing further having a slidable access control device coaxially coupled thereto; 2) engaging the slidable access control device with a shifter to slide the slidable access control device with respect to the bushing; and 3) sliding the slidable access control device between an open position wherein a tool is allowed to pass through the window and the opening and into the lateral wellbore and a closed position wherein the tool is prevented from passing through the window and the opening mad into the lateral wellbore.
U.S. Pat. No. 5,730,224 teaches two key profiles with one is a reverse of the other.
U.S. Pat. Nos. 7,325,617 and 7,552,779 to Murray teach a system allowing for sequential treatment of sections of a zone. Access to each portion can be with a sliding sleeve that has a specific internal profile. Pump down plugs can be used that have a specific profile that will make a plug latch to a specific sleeve. Pressure on the plug when latched allows a sequential opening of sleeves while zones already affected that are below are isolated. The pump down plugs have a passage that is initially obstructed by a material that eventually disappears under anticipated well conditions. As a result, when all portions of a zone are handled a flow path is reestablished through the various latched plugs. The plugs can also be blown clear of a sliding sleeve after operating it and can feature a key that subsequently prevents rotation of the plug on its axis in the event is later needs milling out.
U.S. Pat. No. 9,611,727 to Campbell, et al. teaches an apparatus and method for fracturing a well in a hydrocarbon bearing formation. The apparatus includes a valve subassembly assembled with sections of casing pipe to form a well casing for the well. The valve subassembly includes a sliding piston that is pinned in place to seal off ports that provide communication between the interior of the well casing and a production zone of the formation. A dart having a cup seal can be inserted into the well casing and propelled by pressurized fracturing fluid until the dart reaches the valve subassembly to plug off the well casing below the valve subassembly. The force of the fracturing fluid against the dart and cup seal thereof forces the piston downwards to shear off the pins and open the ports. The fracturing fluid can then exit the ports to fracture the production zone of the formation.
U.S. Pat. No. 9,739,117 to Campbell, et al. teaches a method and apparatus for selectively actuating a downhole tool in a tubular conduit. An actuator tool has an actuator mandrel having an actuator bore through and a bypass and a profile key to selectively engage the downhole tool. The downhole tool has one or more profile receivers adapted to actuate the downhole tool. The actuator tool is conveyed into the tubular conduit and the actuator tool and the downhole tool are engaged if the profile key and the profile receiver match, and the actuator tool and the downhole tool are non-engaged if the profile key and the profile receiver do not match. Fluid may be circulated through the actuator bore to flush or wash ahead of the actuator tool.
US Patent Publication No. 2003/0173089 to Westgard teaches a full bore selective location and orientation system including a nipple installable in a tubular string and having internal location and orientation features of known configuration and a locating device runnable within the tubular string and having location and orientation features engageable with said internal features of said nipple. A method of locating and orientating a downhole tool including installing a tubular nipple having a particular inside dimensions configuration in a tubular string running a locating device having a complementary outside dimensions configuration to engage with said inside dimensions configuration and rotating said locating device to a position where a biased member extends from said locating device into a recess in said tubular member.
US Patent Publication No. 2015/0226034 to Jani teaches an apparatus and related methods for selectively actuating sliding sleeves in sub members which are placed downhole in a wellbore, to open ports in such sub members to allow fracking of the wellbore, or to detonate explosive charges thereon for perforating a wellbore, or both. A simplified dart and sleeve is used which reduces machining operations on each. The dart is preferably provided with coupling means to permit a retrieval tool to be coupled thereto, which upon the retrieval tool being so coupled allows a bypass valve to operate to assist in withdrawing the dart from within the valve subs. Upward movement of the retrieval tool allows a wedge-shaped member to disengage the dart member from a corresponding sleeve to allow the dart to be withdrawn.
US Patent Publication No. 2014/0209306 to Hughes, et al. teaches a wellbore treatment tool for setting against a constraining wall in which the wellbore treatment tool is positionable. The wellbore treatment tool includes a tool body including a first end formed for connection to a tubular string and an opposite end; a no-go key assembly including a tubular housing and a no-go key, the tubular housing defining an inner bore extending along the length of the tubular housing and an outer facing surface carrying the no-go key, the no-go key configured for locking the no-go key and tubular housing in a fixed position relative to the constraining wall, the tubular housing sleeved over the tool body with the tool body installed in the inner bore of the tubular housing; and a sealing element encircling the tool body and positioned between a first compression ring on the tool body and a second compression ring on the tubular housing, the sealing element being expandable to form an annular seal about the tool body by compression between the first compression ring and the second compression ring.
US Patent Publication No. 2015/0218916 to Richards, et al. teaches circulating sleeves that can be opened and closed and permanently closed. A completion system includes a completion string having a circulating sleeve movably arranged therein, the circulating sleeve having a locking profile defined on an outer radial surface thereof and a shifting profile defined on an inner radial surface thereof, a service tool configured to be arranged at least partially within the completion string and including a shifting tool having one or more shifting keys configured to mate with the shifting profile. When the shifting keys locate and mate with the shifting profile, an axial load applied on the service tool axially moves the circulating sleeve, and a release shoulder assembly arranged within the completion string and comprising a release shoulder that defines a channel configured to receive a locking mechanism occluded within the channel until the release shoulder is moved axially.
Canadian Patent No. 2,412,072 to Fehr, et al. teaches a tubing string assembly for fluid treatment of a wellbore. The tubing string can be used for staged wellbore fluid treatment where a selected segment of the wellbore is treated, while other segments are sealed off. The tubing string can also be used where a ported tubing string is required to be run in in a pressure tight condition and later is needed to be in an open-port condition.
Alternative and/or improved designs which allow for consistent and reliable engagement and actuation of subsurface valves, as well as improved sealing, are always of extreme interest to the fracking industry.